1. Field
The present invention relates generally to switching converters. More specifically, the present invention relates to embodiments for average current mode control for multi-phase switching power converters.
2. Background
Power management plays an important role in the current day electronics industry.
Battery powered and handheld devices require power management techniques to extend battery life and improve the performance and operation of the devices. One aspect of power management includes controlling operational voltages. Conventional electronic systems, particularly systems on-chip (SOCs) commonly include various subsystems. The various subsystems may be operated under different operational voltages tailored to specific needs of the subsystems. A voltage regulator, which may also be referred to as a “voltage converter” or a “power converter,” may be employed to deliver specified voltages to the various subsystems. Voltage regulators may also be employed to keep the subsystems isolated from one another.
A voltage regulator may comprise a switching voltage converter. Switching voltage converters may convert between a higher input voltage and a lower output voltage using one or more electronic switches in conjunction with energy storage devices (inductors or capacitors) to transfer energy between a higher external DC power supply voltage and a lower integrated circuit voltage. One advantage of a switching voltage regulator compared to a linear voltage regulator is greater efficiency.
A switching converter may be based on voltage mode or current mode control techniques. Conventional fixed frequency current mode control techniques include peak current mode control, valley current mode control, and average current mode control. Peak and valley current mode control may be susceptible to sub-harmonic oscillations and may require external slope compensation in addition to a synchronizing ramp. Therefore, peak and valley current mode control techniques may require more complex circuits and, hence, large silicon area.
Conventional average current mode control architectures inherently have no sub-harmonic problem. The main distinguishing feature with respect to peak and valley current mode control is that conventional average current mode control uses a high gain and wide bandwidth current error amplifier. This may force the average current of a switching converter to follow a load current with very small error. Advantages of conventional average current mode control include no requirement of compensation ramp, large noise margins, excellent voltage and current regulations, and input voltage and output voltage feed forward control. Because of two error amplifiers, one for voltage and another for current, this architecture implementation is complex and compensation of the control loop becomes quite challenging. The challenge further grows when an average mode technique is used to implement multi-phase converters.
A need exists for an enhanced switching power converter. More specifically, a need exists for embodiments related to a simplified switching power converter that has advantages of conventional average current mode architectures and can easily be extended to multi-phase without sacrificing performance.